Communication methods using the IIC protocol have long been used to communicate between different devices in electronic apparatus through two signal lines: a serial clock line referred to as the SCL line and a serial data line referred to as the SDA line. In IIC communication, while processing a command, a slave device can hold the SCL signal at the low level to indicate that it is busy and suspend data transmission to the master device.
The slave device may also hold the SCL signal at the low level, however, when it fails to receive the SCL and SDA signals sent from the master device correctly. To address this issue, Patent Reference 1 describes a communication system in which the master and slave devices are interconnected by a report line for reporting anomalies. In the communication system described in Patent Reference 1, when an anomaly is detected by a detection means provided for detecting anomalies occurring in IIC communication, one of the devices notifies the other device of the occurrence of the anomaly through the report line.